Center pivot and linear move irrigation systems have become an essential component in present day commercial agriculture since their introduction over sixty years ago. The first irrigation systems suffered from many mechanical and design shortcomings which have resulted in many improvements throughout their existence. One notable improvement in the art was the introduction and development of electronic control and drive systems used to control the operation of the irrigation system and self-propel the irrigation system through the field. Notwithstanding the benefits attributed to this improvement, one particular shortcoming of the electronic control and drive systems known in the art is that the actual ground speed of the irrigation system is often less than a predetermined speed that is set at the commencement of operation due to field conditions.
Irrigation systems known in the art set a predetermined speed for each tower at the commencement of operation. The predetermined speed is set such that the irrigation system applies a fixed amount of an applicant, at a given flow rate, over a defined area of an agricultural field, in a defined amount of time. The speeds of these current irrigation systems are set and maintained throughout operation strictly based on relative position of the towers; however, the tires of the towers often become bogged down or slip in mud that is present in the depression of the tire's track. Water collects in the depression created as the tires traverse the fields and the depressed track's muddy condition and associated tire slippage often cause the actual ground speed of the irrigation system to be less than the predetermined irrigation speed set at the commencement of the application. When the actual ground speed is less than the speed required to apply an applicant at a given rate, over a desired area, in a given amount of time, the result is that a portion of the field receives too much applicant. When the amount of applicant is fixed, like when applying fertilizer, herbicide, or pesticide, too much applicant is applied to a portion of the field and no applicant is applied to the portion of the field remaining when the fixed amount of the applicant is exhausted.
There are many adverse consequences that can be avoided by overcoming this shortcoming in the prior art, including, but not limited to: field damage, reduction of maximum crop yield due to over or under application of the applicant, and multiple economic inefficiencies due to the costs associated with obtaining, purchasing, and delivering additional applicant to complete the application of an applicant on the field. Therefore, a need exists in the art for an irrigation system that monitors the actual ground speed of the irrigation system and adjusts the speed of the irrigation system's drive system to maintain an actual ground speed about equal to the predetermined application speed such that the irrigation system reaches a predetermined user-defined end destination in a predetermined amount of time.